The present inventions are related to I/O expansion devices that enable a system thereof to expand inputs/outputs by connecting it to parallel interfaces of PC/AT or the PC/AT-compatible personal computers (or parallel input/output connectors equivalent to the parallel interfaces), and apparatus applied with I/O expansion devices and methods applied with the device and the apparatus.
As for desktop personal computers, their expansion is ordinarily carried out by inserting an expansion board in the body of the computers. As for the PC/AT or PC/AT-compatible personal computers, their expansion is ordinarily carried out to insert an expansion board based on so-called ISA bus standard into a bus slot. As for notebook-sized portable personal computers, an expansion board for the desktop personal computers can be installed by means of connecting an expansion box such as a docking-station.
Recently, the PCMCIA standard is established, and models that can be extended by inserting an IC card (called a PC card) suitable for this standard into the card slot are in the market.
In the case where the expansion is carried out by inserting the expansion board in the body like the desktop computers, a case of the body must be opened. This is troublesome and a difficult work for persons not having any knowledge of computer.
As for the portable personal computer, its advantage of portability was lost very much if it is connected to a docking-station, and extra expense is required to purchase the docking station.
An expansion method of inserting an IC cad in accordance with the PCMCIA standard into the card slot requires to purchase an expansion board for newly additional expansion, because a desktop computer does not ordinarily support the card slot. The PCMCIA standard has some restrictions of IC card size because it has been derived from the expansion memory cards. Therefore, the expansions with the IC card are limited.
To solve these problems, it is an object of the present inventions to provide I/O expansion devices for additional inputs and outputs without inserting the expansion board in the bus slot and inserting the IC card into the card slot, and apparatus and methods applying the devices.
And it is an object of the present inventions to apply for various uses and provide highly portable personal computers, by means of inserting into the body of the computers like the IC card to apply the I/O expansion device to them.
An I/O expansion device according to the present inventions enables to expand inputs and outputs of a personal computer by connecting it to a parallel interface of the personal computer, and includes a connector for connecting the inputs and outputs to a parallel interface; and an I/O expansion circuit connected to the connector, having data input to input four or five bit data in a first register equivalent to a data register in the parallel interface, data output to output four bit data to a second register equivalent to a status register in the parallel interface, and control input to input a signal from a third register equivalent to control register of a parallel interface,
wherein the I/O expansion circuit has a plurality of four bit input/output ports and a four bit data bus for transferring data between these input/output ports and data input or data output, and outputs four bit data provided from the data input to one of the input/output ports or outputs four bit data provided from one of the input/output to the ports data output according to control from the control input.
The I/O expansion device according to one aspect of this invention is connected to the parallel interface of the personal computer, and inputs and outputs of the personal computer are allowed to be expanded by selecting one of the input/output ports according to the control the control input and executing reading and writing of the selected input/output port.
An I/O expansion circuit according to the present inventions has a plurality of four bit input/output ports, a control input for inputting a signal for controlling the operation of the circuit, a data input for a command for selection of one of the input/output ports and read/write of the selected input/output port and 4-bit data to write, and a data output for outputting status of one of the input/output ports as 4-bit data,
wherein the I/O expansion circuit has a write data bus for transferring data from the data input to the input/output ports, and a read data bus for transferring data from the input/output ports to the data input, a register, which is provided for each input/output port, for fetching and outputting status of the write data bus, and control circuit for fetching the command for selecting one of the input/output ports and setting operation mode in transition of a strobe which is one of control input, and the control circuit makes the status of the selected input/output port output from the data outputs when the fetched command is read mode, and makes 4-bit data provided to the input/output port in the returning transition of the strobe fetched into the register of the selected input/output port and output from the selected input/output port.
The higher speed operation is expected because this I/O expansion circuit comprises two unidirectional 4-bit data bus of the write data bus and the read data bus. An external storage device according to the present inventions comprises a memory, is able to provide data stored in the memory to a personal computer via a parallel interface of the personal computer or store data from the personal computer, and comprises a connecter for connecting to the parallel interface, and an I/O expansion circuit having a data input for inputting four or five bits of a first register equivalent to a data register in the parallel interface, a data output for providing four bit of a second register equivalent to a status register in the parallel interface, and control input for inputting a signal from a third register equivalent to a control register via the connector,
wherein the I/O expansion circuit comprises 4-bit inputs/outputs connected to an address pin, a data pin and a pin for control of the memory, and a 4-bit data bus for transferring data between the input/output ports and the data input or data output, and outputs 4-bit data provided to one of the input/output ports.
In the external storage device, emulating the operations of the memory by turning status of the input/output ports materializes access to the memory. In this way, the present invention provides an external storage device which is connectable to the parallel interface.
Methods for access to an external storage device according to present inventions to connect the external storage device to a parallel interface of a personal computer and to read data stored in a memory of the external storage device by means of writing data into a data register and a control register of a personal computer included, putting one of input/output ports of an I/O expansion circuit connected to data pins of a memory into read mode, setting address to write to the memory, making data written at the address to be output by writing 4-bit data to one of input/output ports of an I/O expansion circuit connected to pins for control of the memory, and reading the data memory by reading the data output from one of input/output ports of an I/O expansion circuit connected to data pins of the memory.
According to this method for access to an external storage device, operation of the memory is emulated, so that it is successfully carried out to write data in the memory with the personal computer or to read data in the memory.
Methods for access to an external storage device according to present inventions to connect the external storage device to a parallel interface of a personal computer and to write data into a memory of the external storage device by means of writing data into a data register and a control register of a personal computer, setting address to write to the memory, setting data to be written to one of input/output ports of an I/O expansion circuit connected to data pins of the memory, writing the into the memory by operation of writing data at the address to be output by writing 4-bit data to one of input/output ports of an I/O expansion circuit connected to pins for control of the memory in sequence.
An I/O extension unit according to the present invention has the I/O expansion circuit wherein read/write of input/output ports is controlled by one bit of the control input that outputs 4-bits data from input/output port by writing the 4-bit data provided from the data input to the input/output ports selected by the remaining three bits of the control input, or may output 4-bit data provided to the input/output ports selected by the remaining three bits of the control input to the data output.
In this I/O extension unit, read/write of the input/output ports are controlled by one bit of the control input, one of the input/output ports is selected by remaining three bits, and 4-bit data from the data input is written to corresponding input/output port or 4-bit data provided to corresponding input/output port is output to the data output, so that higher speed operation is successfully realized.
A computer according to the present inventions is characterized in having a parallel interface and that a program for access to an external storage device as a drive when the external storage device is connected to the parallel interface is written in a ROM of the computer.
And a computer according to the present inventions having a microcontroller formed on monolithic integrated circuit with a parallel interface which input and output at least 4-bit data and a ROM which stores a program for operating the microcontroller, wherein the parallel interface is connectable to a storage device having a memory and an I/O external circuit which can exchange at least 4-bit data between the parallel interface and the memory, address selection and control of the memory through the I/O expansion circuit and exchange of data at desired address of the memory is carried out by the program written in the ROM.